SOLUTION: Simplify the expression by using a double angle formula. 2sin((2pi)/(11))cos((2pi)/(11)) I think it may be sin((4pi)/(11)). I am not sure on this and I could use the help.

Question 596137: Simplify the expression by using a double angle formula.
2sin((2pi)/(11))cos((2pi)/(11))
I think it may be sin((4pi)/(11)).
I am not sure on this and I could use the help.
Answer by jim_thompson5910(35256) (Show Source): You can put this solution on YOUR website!
Using the identity

2*sin(x)*cos(x) = sin(2x)

we get

$2\sin\left(\frac{2\pi}{11}\right)\cos\left(\frac{2\pi}{11}\right) = \sin\left(2\times\frac{2\pi}{11}\right) = \sin\left(\frac{4\pi}{11}\right)$

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So
$2\sin\left(\frac{2\pi}{11}\right)\cos\left(\frac{2\pi}{11}\right)=\sin\left(\frac{4\pi}{11}\right)$

which means you are 100% correct. Nice job.
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